Expansion valve sensor bulb

ABSTRACT

A sensor system for controlling an expansion valve in a phasechange refrigeration system in which the bulb is a long spiral coil integral with the capillary tubing which communicates with the valve controlling chamber of the expansion valve. In a preferred embodiment, the bulb consists of two or more such coils connected in series in the tubing and disposed in parallel juxtaposition.

United States Patent Webber Mar. 11, 1975 [5 EXPANSION VALVE SENSOR BULB 2,548,866 4/1951 garter 236/299 D 2,940,278 6 1960 hom son 6 208 [761 lrrverrtorl f Webberr BOX 217, 3,413,440 11/1968 Drugn nd 236/49 1) Indianapolis, Ind. 46206 [22] Filed: Nov. 9, 1973 Primary Examiner-Meyer Perlin [211 pp No 414,313 Attorney, Agent, or Firm-Wi11iam R. Coffey [52] U.S. Cl 62/225, 236/99, 73/3682 [57] ABSTRCT 51 Int. Cl. F2Sb 41/04 A Sensor Sysrem for corrrrollrrrg arr erparrsrorr Valve 58 Field of Search 62/203, 204, 205, 206, a Phase-Change refrigeration System Whrch the bulb 62/207, 208 209 210, 21 1, 212, 213, 214 is a long spiral coil integral with the capillary tubing 222 223 224 225; 23 /99 73/3 2 which communicates with the valve controlling chamber of the expansion valve. In a preferred embodi- [56] References Cited merit, the bulb consists of two or more such coils con UNITED STATES PATENTS nected in series in the tubing and disposed in parallel juxtaposition. 1,640,243 8/1927 Lawler 236/99 D 2,250,274 7/1941 Raney 5 Claims, 4 Drawing Figures EXPANSION VALVE SENSOR BULB It is conventional in a phase-change refrigeration system to control the flow of liquid refrigerant to the evaporator through the medium of an expansion valve which includes a controlchamber having a pressureresponsive wall operatively connected to the valve head, with a ductile capillary tube communicating with the interior of the chamber and attached, at its other end, to a temperature sensor bound in heat-exchanging contact to a conduit of the refrigerant circuit, usually the return conduit leading from the evaporator to the compressor, the closed system consisting of the sensor, the tube and the chamber, being charged with a phasechange fluid; whereby the sensor or bulb will be af fected by the temperature of fluid flowing through the said conduit to vary the pressure currently applied to the movable wall of the chamber and thereby to actuate the expansion valve head.

Conventionally, the bulb (which may take any one of several conventional forms) is telescopically attached to the distal end of the capillary tube by soldering or the like. In some cases, the bulb consists ofa long spiral coil of tubing, usually enclosed in a housing, with the distal end of the coiled tubing projecting longitudinally from the housing and closed. The assembly of such a bulb with the tubing which is, or is to be, connected to the valve control chamber, after the charge for the control system has been entered thereinto, is fraught with some difficulty and almost inevitably results in the loss or escape of an indeterminate amount of the intended charge.

These conventional bulbs are relatively long and cannot be effectively secured to the selected conduit of a refrigeration circuit by means of a single strap-type clamp, wherefore two or more clamps are conventionally used for that purpose.

The primary object of the present invention, then, is to provide an improved sensing system for the control of an expansion valve in a phase-change refrigeration circuit. A further object is to provide, in such a system, a bulb which is integral with, and directly formed from, the distal region of the conventional capillary tube by winding that tube region about a suitable mandrel into a long spiral coil.

Another object of the invention is to make such a bulb easier to install by tucking its distal extremity into the interior of the formed coil, or preferably to thread the distal extremity region of the tube longitudinally entirely through the length of the coil.

Still another object of the invention is to improve such a sensor bulb by winding the distal region of the capillary tube in one direction to form a relatively short coil, then, through a transition, carrying the tube to a point significantly offset from the axis of said coil and then winding the same tube about an offset axis to form a second relatively short coil disposed in paralleljuxta position to the first coil; whereby the complete bulb comprises two relatively short lengths to be held in parallel contact with each other and in heat-exchanging contact over a relatively wide area with the same length of a conduit in the refrigeration circuit. By this means, the temperature of a longitudinally-short volume of fluid in such conduit can be effectively measured to render the contents of the bulb, tube and chamber more delicately responsive to the temperature of the refrigerant flowing in the conduit.

Further objects of the invention will appear as the description proceeds.

To the acomplishment of the above and related objects, this invention may be embodied in the forms illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific constructions illustrated and described, so long as the scope of the appended claims is not violated.

In the drawings:

FIG. I is a more or less diagrammatic illustration of a conventional expansion valve;

FIG. 2 shows a fragment of a capillary tube with its distal region integrally wound into a long spiral coil, the distal extremity of said tubing being closed and extend ing beyond the adjacent end of the coil;

FIG. 3 is a perspective view of the same kind of coil but in which the distal extremity of the tubing has been threaded longitudinally rearwardly through the entire length of the coil; and

FIG. 4 is an illustration of a bulb formed to provide two juxtaposed sections and installed, through a single clamp, upon a conduit of a refrigeration circuit.

Referring more particularly to FIG. 1, the reference numeral 10 indicates generally an expansion valve of known characteristics having an inlet 11 and an outlet 12. The valve housing is formed to provide a control chamber (not shown) in its upper end for actuating a valve head (not shown) which controls flow between the inlet 11 and outlet 12.

A fitting 13 opens into the control chamber and has connected thereto a ductile capillary tube I4. As thus far described, the structure is conventional, and conventionally a separate bulb or sensor of known con struction is suitably secured to the distal end of the tubing 14.

According to the present invention, on the other hand, the distal region of the tube 14 itself is wound into a long spiral coil 15 which may be secured in intimate contact with a conduit 17 ofa refrigeration circuit by means of, for instance, metal strap type clamps 16. To secure such a long bulb effectively in place for satisfactory heat exchange, it is customary to use at least two clamps.

The distal extremity 18 of the tube 14 extends axially beyond the adjacent end of the coil 15 and is closed as at 18.

It will be seen that, when the bulb 15 is integral with the tubing 14, the bulb, the tubing and the valvecontrolling chamber may be charged with a suitable refrigerant under accurately measured compression by injecting the fluid through the originally open distal end of the tubing and then quickly closing the distal extremity of the tube, substantially without any escape of the compressed fluid.

It is sometimes found that, in some installations, the extending tail 19 of the tubing interferes with installa tion of the bulb 15 at precisely the desired point on the conduit 17; and therefore, I prefer to turn to the expedient illustrated in FIG. 3.

The tubing 24 is identical with the tubing 14 and is wound into a coil 25 substantially identical with the coil 15. However, a longer extent 29 of the tubing is left beyond the distal end of the coil and may be turned back and threaded through the entire length of the coil 25 as illustrated in FIG. 3. Here, again, the control system can be charged through the distal extremity of the tubing 24 before that extremity is closed as at 28.

A still further advance is illustrated in FIG. 4 in which the tubing 34, which is like the tubing 14, is wound into a first long spiral coil as at 35 and then, through a transition 36, the distal portion of the tubing 34 is moved to an offset position and the winding is continued to form a second long spiral coil 37 parallel to, substantially identical in length with and preferably in intimate juxtaposition to the coil 35. Preferably, the distal extremity of the tubing is turned back and threaded through the entire length of the coil 37 to leave its tip 38 sufficiently exposed to permit charging of the system followed by closure of the tip 38.

Not only does this expedient shorten the bulb so that it may be effectively secured in place on the conduit 17 by a single clamp 39, but a more sensitive response of the valve controlling system is achieved because, while the total length of contact between the conduit 17 and the bulb is the same as with the longer bulbs of FIGS. 2 and 3, a much shorter volume of fluid within the conduit l7 affects the bulb at any one instant so that variations in temperature of the fluid along the length of the conduit 17 are minimized.

I claim as my invention:

1. In combination with an expansion valve having an actuator chamber, the invention which comprises a ductile capillary tube having its proximal end in communication with said chamber, the said tube having its distal region formed to define a long spiral coil closed at its extremity, and the distal region of said tube being threaded back through the entire length of said coil to project beyond the proximal end of said coil.

2. In combination with an expansion valve having an actuator chamber, the invention which comprises a ductile capillary tube having its proximal end in communication with said chamber, the said tube having its distal region formed to define a long spiral coil closed at its extremity, and the distal region of said tube being formed to define also a second long spiral coil disposed in parallel relation to said first-named coil.

3. The invention of claim 2 in which said two coils are substantially equal in length and arranged for securement by a single clamp to a conduit of a phase-change refrigeration circuit dominated by said valve.

4. The invention of claim 2 in which said two coils lie in intimate juxtaposition.

5. The invention of claim 4 in which said two coils are arranged in series for successive fluid flow therethrough. 

1. In combination with an expansion valve having an actuator chamber, the invention which comprises a ductile capillary tube having its proximal end in communication with said chamber, the said tube having its distal region formed to define a long spiral coil closed at its extremity, and the distal region of said tube being threaded back through the entire length of said coil to project beyond the proximal end of said coil.
 1. In combination with an expansion valve having an actuator chamber, the invention which comprises a ductile capillary tube having its proximal end in communication with said chamber, the said tube having its distal region formed to define a long spiral coil closed at its extremity, and the distal region of said tube being threaded back through the entire length of said coil to project beyond the proximal end of said coil.
 2. In combination with an expansion valve having an actuator chamber, the invention which comprises a ductile capillary tube having its proximal end in communication with said chamber, the said tube having its distal region formed to define a long spiral coil closed at its extremity, and the distal region of said tube being formed to define also a second long spiral coil disposed in parallel relation to said first-named coil.
 3. The invention of claim 2 in which said two coils are substantially equal in length and arranged for securement by a single clamp to a conduit of a phase-change refrigeration circuit dominated by said valve.
 4. The invention of claim 2 in which said two coils lie in intimate juxtaposition. 